Invader #2

[Interceptor398]

Did it loose any coolant?

[kawhead]

idk if the crank seal caused it but imo it'll need a piston

[JDmatt]

I keep saying this... crank seals good or bad will not have any effect on compression. Once the piston is past the intake port, it is all up to the piston, rings, cylinder, head and gasket to make the compression.

Crank seals only affect the air/fuel mix. Too much air and the cylinder will run hot which is what melts pistons and such.  Or too much air and it won't start.

I'd look at cylinder wear, or possibly stretched  cylinder studs. The acorn type nuts on the top can bottom out when they are torqued down and make you think the head is tight when it is not. Add a washer or two under them, or replace the studs.

You might be on to something there with the studs.  That would explain the lack of compression without anything obviously wrong. 

[JDmatt]

Did it loose any coolant?

Nope, didn't appear to. 

[Lloyd (ljm)]

hey Matt

 What gaskets did you use when you had the engine apart?

 I have had similar issues when I used Winderosa gaskets, not always but sometimes.

[kawhead]

just because you cant see damage thru the exaust port doesnt mean the piston is ok....and, no, crank seals wont have an affect on compression......untill it makes that cyl run lean

[JDmatt]

just because you cant see damage thru the exaust port doesnt mean the piston is ok....and, no, crank seals wont have an affect on compression......untill it makes that cyl run lean

As I mentioned earlier, I pulled the head too.  There is no damage.  Lloyd, I didn't replace the gasket yet.  I'm getting ready to move, so after my new shop is set up, I'll get back to this project. 

[kawhead]

if i had it tore down that far i'd pop the cyl off....what do you think the low comp. is caused by?

[JDmatt]

LOL, I didn't take it apart any further because my shop is already a huge mess and I didn't want to make it  even worse before I can get organized. 

[kawhead]

i understand the mess...my little boat shop looks like a rip tide went thru ...bet you a crown and water at waconia it has a 4 square seize

[JDmatt]

My Invader is back together and running again.  As it turns out it did have a little meltdown that I couldn't see until I pulled the cylinders, which I believe was caused by dirty carbs.  The previous owner had told me he had cleaned them last year, but I shouldn't have listened, they were pretty messy.  Complete rebuild, cylinder and piston off a spare engine with new SPI rings both sides, Wiseco Gaskets and seals. 

I threw one of my New Breed ski conversions on it too, unfortunately the blue does not match very closely. 

[kawhead]

4 square is most often dirty carbs/lean....i clean the carbs on mine every year even with stabilized fuel, don't want to get out of practice